Pulley-block



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PULLEY BLQUK. No. 572,766. Patented Dec. 8, 1896.

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PULLBY BLOGK. No. 572,766. Patentd Dec. 8, 1896.

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No. 572,766. r Patented Deo. 8. 1896.

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' j MmQW UNITED STATES PATENT QFFICEQ OLIVER MJMOWAT, OF PITTSBURG, PENNSYLVANIA. I

PU LLEY-BLOCK.

SPECIFICATION forming part of Letters Patent No. 572,766, dated December 8, 1896.

Application filed July 14, 1896. Serial No. 599,069. (No model.) I

To all whom it may concern.-

Be it known that I, OLIVER M. MOWAT, of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Pulley-Blocks, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming part of this speciv which the load may also be lowered slowly and uniformly, either by hand or by the automatic action of theload itself, as desired.

In the drawings, in which similar numerals indicate corresponding parts, 2 and 3 represent the main brackets forming the frame of the block, these brackets beingfirmly bolted together with an interposed hook-bracket, as shown, and being of the general form shown in Figs. 1 and 2, respectively. The bracket 2 is provided with an inwardly-projecting bearing 4 for the hub or collar 5 of the chainwheel 6, over which wheel passes the liftingchain 7, the bracket 3 likewise having a bearing 9 for the opposite portion 10 of this hub or collar. Secured to and preferably formed integral with the hub of the chain-wheel 6 is an internal gear-wheel 11, whose teeth are engaged by the teeth of a pinion 12, whose shaft is provided with a toothed wheel 13, these wheels 12 and 13 preferably being cast integral with each other. The toothed wheel 13 intermeshes with a pinion 14, secured to the driving-shaft 15, this shaft extending through the hub of the chain-wheel 6 and having keyed thereto a hub or collar 15,with a projecting annular flange, as shown, this hub having loosely mounted thereon a friction-wheel 16, whose rim is provided with ratchet-teeth 17 engaged by a pawl 18, pivoted to the frame, which prevents rotation of of the driving-chain wheel forces the shoes.

against the friction-wheel and causes these two wheels to move as one.

The operation is as follows: hen it is desired to lift a load, the operator rotating the driving-chain wheel clockwise by means of the hand-chain, the screw-threads cause the shoes to bind upon the friction-wheel16, and this and the chain-wheel move together with the driving-shaft, the lifting-chain wheel being rotated by. means of the intermediate gearing. When stopped in any position, the pawl engaging the teeth upon the frictionwheel locks the same from rotation in the opposite direction and likewise locks the driving-chain wheel, the shoes being arranged at such a distance from the center that a sufficient moment or lever-arniis afforded for this purpose. If it is desired to lower the load, the driving-chain wheel being rotated in the opposite direction, the weight of the load causes the driving-shaft to rotate, so that the threads thereon follow up those within the chain-wheel and maintain the same relation thereto, the shoes sliding with frictional resistance over the face of the friction-wheel. If it is desired that the load shall lower auto-- matically without hand rotation of the chainwheel counter clockwise, the shoes are moved inwardly to such a point that their moment is not sufiicient to overcome, but is slightly overbalanced by,tl1e load,in which case, upon releasing the chain-wheel, theload will automatically and slowly lower itself, the shoes moving over the friction-wheel and giving sufficient resistance to insure a slow and uniform downward movement of the load.

The advantages of my invention will be apparent to those skl'lled in the art, since a pulley-block is afforded by which the load may be lifted and locked in any position and lowered either by hand or by the action of the load itself, the shoes being easily and quickly adjusted to the different positions suitable for such action.

The device is simple and compact, and the connecting-gearing is efficient and takes up a small amount of space.

Modifications in the form, construction, and relative arrangement of the parts of the device will be suggested to those skilled in the art Without departing from my invention, since What I claim as new, and desire to secure by Letters Patent, is-

1. In a pulley-block, a driving-chain Wheel, a driving-shaft having screw-threaded engagement therewith, radially-movable shoes mounted upon the chain-wheel and arranged to contact with a friction wheel or ring and means for preventing the movement of the friction-wheel in one direction; substantially as described.

2. In a pulley-block, a driving-wheel havin g a screw-threaded engagement with a driving-shaft,and provided with radial slots,shoes adj ustably mounted in said slots, a friction- Wheel revolubly mounted upon the shaft and arranged to contact with the shoes, and means for preventing movement of the frictionwheel in one direction; substantially as described.

3. In a pulley-block, a driving-Wheel having a screw-threaded engagement with a drivin g-shaft,and provided with radial slots,sh0es adjustably mounted in said slots, a friction- Wh'eel revolubly mounted upon the shaft and arranged to contact With the shoes, and a pawl arranged to engage ratchet-teeth upon the friction-wheel; substantially as described.

In testimony whereof I have hereunto set my hand.

OLIVER M. MOXVAT. lVitnesses:

G. I. HoLDsHIP, G. BYRNES. 

